Carrier telegraph circuits



' L. ESPENSCHIED CARRIER TELEGRAPH CIRCUITS C5 Sheets-Sheet 1 FiledOct. 21. 1920 mg E \I|- Ll I I I I I I I I I I I I \H l INVENTOR a fioflgpz imafzwd 4 92i 6' ATTORNEY A E H5 19249 L. ESPENSCHIED CARRIER EELEGRAPH C IRCUITS Filed Oct. 21, 1920 W 76'' ME s Shee ts-Sheet 2 I NV ENTOR fifiwwwfzwd ATTORNEY A rifi a5 1924a 1,490,166

L. ESPENSCHIED CARRI ER TELEGRAPH C IRCUITS Filed Oct. 21, 1920 s SheetsSheet 5 lNVENTOR A 5 6m ATTORNEY till Apr. l5, 3192a.

IhLCYD ESPENSCHIE, OF QUEENS, NEW YQRK, ASSIGZ'KlOR T0 MEJMCAIE TELEPHONE AND TELEGEH COW, A COREQRA'IIQN 0E NEW YGEK.

33H KER/GUI.

To all whom it may concern:

Be it known that l, Lnorn Esrnnsomnn, residing at Queens, in the county of Queens and State of New York, have invented certain Improvements in Carrier Telegraph Circuim, of which the following is a specificatio n. V

This invention relates to signaling systems, and more particularly to systems in which telegraph signals are transmitted by means of carrier lines.

oi the objects of this invention is to provide means whereby a telegraph suhscrihers circuit or loop may he associated with the channels of a carrier transmission circuit.

Another object of the invention is to provide means for interconnecting a telegraph suloscrihers circuit or loop with a carrier transmission system in such a manner that signals may be transmitted from the loop to the carrier system, and from the carrier system to the loop, the loop being a low frequency circuit.

Another object of the invention is to provide means for associating a telegraph suhscribers circuit or loop with the transmitting and receiving channels of a carrier transmission system, said means being so arranged that signals transmitted to t e loop will not be repeated from the loop back to the carrier transmitting channel associated with the circuit from which the signals originated.

Another object of the invention is to provide means for associating a local telegraph subscriber-"s circuit or loop with the carrier channels of a through telegraph repeater arrangement associating two carrier transmission line sections.

Another olojectof the invention is to provide an arranemcnt tor associating a tele graph suhscri rs circuit or loop with the oppositely directed mrrier channels of a telegraph repeater arrangement interconnecting two carrier transmission line c rcuits, said means heing so arranged that signals received by the loop will not be re-. peated hack in the they came.

Other and further objects of the invention will be clear from the following description when read in connection with the accompanying drawing, Figures 1, 2 and 3 of direction from which which constitute circuit diagrams of the dii"= ferent embodiments of the invention.

Referring to Fig. 1, which shows a sub-- scrihers loop associated with the channels of a carrier telegraph repeater in. such a manner as to he 0 erated on a half duplex basis, MLE and VlLW respectively designate two line sections of a carrier transmission circuit. These line sections are interconnected by a repeater arrangement, in which each telegraph channel in a given direction is provided with separate amplifying means. The repeater apparatus comprises common transmitting and receiving circuits TLE and BLE, associated with the carrier line section MILE, and common transmitting and receiving circuits TUW and RLW' associated with the transmission line MLYV. In order to render th transmitting and re ceiving circuits conjugate with respect to each other, the receiving channels are associated with the main line sections ML and MLE throu h balanced transformers l0 and 10' of wel -known construction, and the main line sections are balanced by artificial lines or networks MNW and MNE. Several repeater channels for transmitting from west to east may interconnect the receiving circuit RLW and the transmitting circuit TLE, the several repeating channels being associated with said circuits through selective devices such as sharply tuned circuits. But one channel TC transmitting from west to east is illustrated, said channel being associated with the receiving circuit RLW and the transmitting circuit TLE through tuned circuits 11 and 11' respectively. Channel TC includes a transmitting amplifying arrangement TAE, and a receivin amplifying arrangement RAW, said amp ifying arrangements being connected to operate in tandem with respect to through transmission. Each of these amplifying arrangements may be of any well-known character, such, for example, as a vacuum tuhe amplifier. Similarly, repeater channels for transmitting from east to west are associated by means of tuned circuits with the circuits RLE and TLW; but one such channel RC is illustrated, the channel RC being associated with the circuits TLW and ELF respectively by means of sha ly tuned elements 21 and 21'. Transmitting and receiving "amplifiers TAW and TAB are included in the channel El], and are arranged to-cop crate in tandem for through transmission. While it is not inherent in the system thus far described that transmission should not take place simultaneously in opposite directions as regards a given pair of channels, where the system is to be operated upon a half duplex basis it will be understood that, in practice, transmission takes place in a given direction in the one chan nel of a air at one time; that 1s, it transmission 15 taking place from east to west signals will be transmitted only over the channel from east to west, the corresponding channel from west to cast being "dle so far as the transmission of signals is con cerned. When the system is operated in this manner, it is possible to associate a subscribers loop, such as the loop L, with the transmitting and receiving channels, so that the subscribers loop will operate upon a half duplex basis to transmit and receive signals to and from the carrier repeater channels. In order that signals may he received by the loop L from either the channel TC or channel RC, detecting devices DW and DE are associated in lurid es connected across the channels TC and C respectively, between the receiving and. transmitting amplifiers of each channel.

I These detecting devices ma be of any well 'RW are connected in the output circuits of the detectors to control the local circuit 25 of the repeating apparatus RR, included within the dotted lines, said repeating apparatus functioning to repeat signals from the loop to the carrier channels and vice versa.

In order that signals may be transmitted from the loop to the carrier channels, a local circuit 26 is associated with the mechanical repeater RR, said circuit iii-- eluding transmitting relays TE and PW for opening and closing the output circuits of the transmitting amplifiers TAE and TAW respectively, or otherwise interrupting the transmission of carrier oscillations from the transmitting oscillators to the corresponding carrier line section. Since in practice, when a channel is idle, the carrier frequency is continuously transmitted, it will be seen that signals may be transmittedfrom the repeater point by merely interrupting'the carrier frequency normally transmitted through the repeater in the manner indicated. The mechanical repeating apparatus RR comprises a transmitting relay '1 and a receiving relay R. The transmitting relay 'l controls the circuit 26 and includes a main coil 2? arranged in the loo circuit and an auxiliary or looking coi 28 controlled by the receiving relay B. The receiving relay R, upon the other messes hand, controls the continuity of the loop L and includes a main coil 29 in the circuit 25 and an auxiliary or locking coil 30 controlled by the transmittin relay T. The loop L may include a key and a sounder S for transmitting and receiving signals from a suhscrihers station.

Further details of the apparatus will be understood from the description of the operation, which is as follows: Normally, a carrier frequency is transmitted from east to west from the main line MLE throu h thetransformer 10 into the circuit BL t,

and from thence through the tuned circuits 21, amplifiers RAE and TAW, tuned circuits 21, and transmitt-in circuit TLW', to the line section Similarly, a carrier current is transmitted from west to east from the line section ML, throu h the transformer 10, tuned circuits 11, amplitiers RAW and TAE tuned circuits 11', and transmitting circuit lLE, to the main line MLE. Signals may be transmitted over either of these channels in the appropriate direction by interrupting the carrier frequenc in any welhlrnown manner. li signa s are being transmitted from west to cast, the interruptions in the carrier frequency transmitted over the channel RC act through the detector DE to cause the detector RE to open the circuit 25, thereby deenergizing the coil 29 of the receiving receiving relay ll of the mechanical repeater.

The coil 30 of said relay has its windingshort-circuited over the normally closed contact 31 of the transmitting relay 'l. Consequently, each time the coilfitl is deener gized, the armature of the relay R falls oil and opens the loop circuit, deenergiaing the sounder S in the loop and the coil 2701? the transmitting relay 1. The sounder S, by responding to the interruptions of the loop, records or makes known the signals transmitted through repeater channel RC at the suhsorihers station. At the same time that the coil 27 was deenergized, the normally closed contacts 32 of the relay R are opened, thereby removin a shortcircuit from ahout the coil 28 of t e relay 'l, so that said coil is energized at the same time that the coil Q? is deen'ergized, thus preventingthe armatures from tallin of and tran mitting the signal m the circuit 26 to the cairierchannels. ln a similar nner, if signalsfiare transmitted from west to east, the detector EM" responds to the interruptions of the carrier frequency, and causes the repeating apparatus RR to repeat the signals to the loop L.

Signals may be transmitted from it loop L in opposite directions to the line sections MLE. and MLW respectively, lay opening and closing the loop by means of the hey K. Each time the loop is opened, the coil 27 of the transmitting relay T is deenerllllll lllll nee les mitting amplifiers TAE and TAW, thereby lit) till

interrupting the continuous carrier frequency normally transmitted in opposite directions.

If, while carrier signals are being trans-- mitted through the carrier repeater in either direction, the operator having control of the loop circuit desires to break in or interrupt for the purpose of transmitting, the o rator may transmit a break signal by hol ing open the hey K for an interval, thereby causing the armature of the transmittin relay to fall oil during the continuance o the break. As a conse uence, the transmitting relays TE and W interrupt the carrier frequency normally transmitted to each line section from the channel TC and RC respectively. The continued interruption of thecarrier frequency transmitted over the main line sections a prises the operators associated with the line sections that another operator desires to break in. The falling oil of the armature of the transmitting relay T by intepting contact 31 removes the shortcircuit from about the winding 30, and therefore prevents the armature of the receiving rela R from res ending to interruptions o the circuit will be interrupted, and the detector DW,

acting through the relay RW, opens the circuit 25, thereby causing the armature of the relay R to fall 0% and held open the loop circuit during the continuance or the break. The operator who is sending by opening and closing the loop circuit, mes aware that a break signal is being received, by the fact that the sounder S no longer responds to the' interruption of the loop.

Fig. 2 shows an arrangement somewhat similar to that of Fig. 1, except that th system operates as an open circuit as distinguished from the closed circuit system shown in'l ig'. 1; that is, the signals are transmitted not by interrupting a normally transmitted carrier frequency, but by transmitting groups or trains of carrier oscillations. The, loop itself will be operated, as before, upon a closed circuit sis, so that signals from the loop will be tnsmitted by opening the loop. The carrier apparatus is, therefore, arranged so that when the loop is 0 en, the carrier frequency will be transmitte Similarl ,the apparatus is so arranged that when t e carrier irequcncy is received, the-loop is interru '1? A mechanical'repeater a paratusR is merely indicated schematics. ly in Fig. 2, but will be identical with that shown in Fig. 1. The circuit 25 leading to the receiving relay of the repeater HR is normally closed under the control of a relay R, which is deenergized during periods when the carrier current is not being received. The circuit of the relay R is jointl controlled b the receiving relays RE an RlV associate with the detectors DE and DW. These receiving relays. when dcen'ergized, maintain the circuit of the relay .R' open, but if either relay is energized by a detected train of carrier oscillations, the circuit of the relay R will be closed.

Since the carrier frequency is not normally transmitted through the carrier repeater channels, it is not possible to control the transmission of signals from the loop by interrupting the continuity of the repester channels. Consequently, in the sys tem of Fig. 2, the repeater channels remain intact, but sources of carrier frequency, such as GE and GW, are bridged across the channels TC and RC respectively on the in ut sides of the transmitting amplifiers T E and TAW. These sources may be of any well-known character, .but am'preferably vacuum tube oscillators. The oscillators are normally inoperative, bu-tare arranged to generate oscillations when their circuits are closed, by ms of the normally deenergized transmitting relays TE and TW, which are included serial v in alocal circuit, which is held open by the normally energized relay T in the circuit 26 controlled by the transmitting relay T of the mechanical repeater RR. Additional amplifiers AE and AW may M provided in the. carrier channels. it desi. for the pn e: I

of. securing additional amplification for f through transmission.

' The operation is as follows: Each time theloop L is opened in transmitting signals, the relay T will be deencrgizedby means of the transmitting relay T of the repeating apparatusRR, thereby closing the circuit of the transmitting relays TE and TW. These relays maintain closed the circuits of the oscillators GE and Gl V to transmit trains of oscillations corresponding to the interruptions of the loop L, through the am pliiiers TAE and EAW to the line scnions MLE and MLW respectively. ll signals are being transmitted from west to east through the carrier channel TQ each time a train of oscillations passes through the channel TC the detector DW operates to enlit) Mid

are

lit

llll

iac'

ergize the relay RW, which in turn closes the circuit of the relay R. The relay R, by openinthe circuit 25, causes the receiving relay 3' to repeat the signal to the loop L by opening the loop. In a similar manner, signals transmitted from east to west through the channel RC cause the relay RE to close the circuit of the relay R, which in turn operates through the receiving relay of the repeater RR to open the loop L.

Fig. 3 illustrates a closed circuit system, somewhat similar to that of Fig. 1, except that the frequencies of the several carrier channels transmitted in a given direction are amplified by a common amplifier. For this urpose common amplifiers RAl and RA are associated with common receiving circuits RLW and RLE and common transmitting amplifiers TAE" and TAW are associated with the common transmitting circuits TLE and TLW, The carriers frequencies assigned tov the channels are separated into the proper channels, such as TC and RC, through tuned circuits arranged in the output sides of the receiving amplifiers and the input sides of the transmitting amplifiers; The circuit 25 of the mechanical repeater RR is maintained normally closed by relays R and R" controlled by the detectors DW and DE res ctively. The relays R and R are norma ly energized when carrier currents are being transmitted through the channels TC and RC respectively, but, u on the interruption of transmission of tie carrier frequency through either channel, the corresponding relay is deenergized and opens the circuit 25 to in turn transmit the-signal to the loop L by opening the loop. The relay T in the circuit 26 of the mechanical repeater RE is normally-energized, and maintains the circuit of the transmitting relays TE and TW normally closed. When the loop is interrupted, however, in .transmitting signals, the relay T is deenergized through the action of the mechanical repeater, so that the transmittin rela s TE and TW open the channels T and C tointerrupt the transmission of the normally transmitted carrier frequency to the line sections MLE and MLW respectively.

It will be obvious that the general rinciples herein described may be embo ied in many other organizations widely difi'erent from those illustrated without departing from the spirit of the invention as defined in. the following claims.

What is claimed is:

1. In a signaling stem, two transmission line sections over which carrier currents may be transmitted, a carrier repeater arrange ment for interconnecting the ends of said line sections, said repeater arrament comprising carrier transmitting and carrier receiving channels associated with each line incense section, arrangements for interconnecting the carrier transmitting channel associated with each line section with the carrier receiving channel associated with the opposite line section, said arrangements including means for repeating carrier frequencies incoming from one line section through the interconnected channels to the other line section atthe same frequency, means associated with at least one of said receiving channels for translating carrier currents into low frequency signals, a low fre uency telegraph circuit, and a mechanical to e aph repeater for associating said telegrap circuit with said translating means, whereby carrier signals transmitted from one line section to the other through said carrier repeater arrangement may be repeated to said low frequency telegraph circuit as low frequency signals.

2. In a signaling system, two transmission line sections over which carrier currents may be transmitted, a carrier repeater arrangement for interconnecting the ends of said line sections, said repeater arrangement comprising carrier transmitting and carrier receiving channels associated with each line sect-ion, arrangements for interconnecting the carrier transmitting channel associated with each line section with the carrier receiving channel associated with the opposite line section, said arrangements including means for repeating carrier freqpencies incoming from one line section t rough the interconnected channels to the other line sect-ion at the same frequency, means associated with each of said receiving channels for translating carrier currents into low frequency signals, a low fre uency telegraph circuit,-and a mechanics. repeating arrangement for associating said te egrap circuit with said translatin means whereby carrier signals transmitted from one line section to the other through said carrier repeater ararrangement may be repeated to said low frequency telegraph circuit as low frequency signals. 7

3. In a signaling system, two transmission line sections over which carrier currents may be transmitted, a carrier re cater for interconnecting the ends of sai line sections, said repeater arrangement comprising transmitting carrier channels and recelvin carrier channels associated with each line section, arrangements for interconnectin the carrier transmitting channel associate with each line section with the carrier receiving channel associated with the. opposite line section, said arrangements including means'tor repeating carrier frequencies incoming from one line section through the interconnected channels to the other line section at the same frequency, means associated with at least one of said transmitting channels for translating low frequency signals into carrier currents, a

res

" repeater arrangement comprising transmitting carrier channels and receiving carrier channels associated with each line section, arrangements for interconnectin the carrier transmitting channel associated with each line section with the carrier receiving channel associated with the op its line section, said arrangements inclu ing means for repeating carrier frequencies incoming from one line section through the interconnected channels to the other line section at the same frequency, means associated with at least one of said transmitting channels fortranslating low frequency signals into carrier currents, a low fr uency telegraph circuit and a mechanical te egraph repeater for interconnecting said circuit with said transmitting channels whereb signals transmitted over said telegraph circuit may be re ted to said carrier channels.

5. n a signaling system, two transmission line sections over which carrier currents may be transmitted, a carrier repeater arrangement for interconnecting the ends of said line sections, said repeater arrangement comprising carrier transmittin channels and carrier receiving channe ciated with each line section, arrangements for interconnectin the carrier transmitting channel associat with each line section with the carrier receiving channel associated with the opposite line section, said arrangements including means for repeating carrier frequencies incoming from one line section throu h the interconnected channels to the other line section at the same frequency, means associated with at least one of said receiving channels for translating carrier currents into low frequency si a s, means associated with at least one 0 said transmitting channels for translating low fre- -terconnecting the carrier reeeivin quency signals into carrier currents, a low frequency telegraph circuit and a two-way mechanical telegraph repeater for interconnecting said telegraph circuit with said translating means w ereby carrier signals transmitted from one line section to the other through said carrier repeater arrangement may be repeated to said telegra h circuit as low frequency signals, and w ereby low frequency signals transmitted over said telegrap circuit ma be repeated to said transmission line section as carrier currents.

6. In a signaling system, two transmission line sections over which carrier currents may be transmitted, a carrier repeater I arrangement for interconnecting the ends of said line sections, said repeater arrangement comprising carrier transmittin channels and carrier receiving channe associated with each line section, means for inchannel of each line section with the carrier transmitting channel of the o osite line section, means associated wit at least one of said receiving channels. for translating carrier currents into low frequency signals means associated with at least one of sai transmitting channels for translating low frequency signals into carrier currents, a low frequency tele aph circuit/and a twoway mechanical to egraph repeater for interconnecting said telegraph circuit with said translat ng means, whereby carrier si nals transmitted from one line section to 0 other through said carrier re eater arran ement may be repeated to sai tele aph cucuit as low frequency signals, an .whereby low fre uency signals transmitted over said telegrap transmission line sections as carrier currents, and means associated with said mechanical telegraph repeater for preventing received signals repeated thereby from actuating the transmittingelement of the repeater to repeat the signals back in the direction from which the originated.

In testimony whereo I have signed my name to this specification this 19th day of October, 1920.

LLOYD ESPENSCHIED.

circuit may be repeated to said. 

